What best describes the role of abrasiveness in an emery board?

The role of abrasiveness in an emery board is primarily to smooth the edges of hair and nails. Emery boards are made from a cardboard base coated with an abrasive material, which can effectively shape and refine the tips of nails by removing rough edges and creating a polished finish. When used on hair, the abrasive surface can help in smoothing split ends or rough hair tips, contributing to an overall neater appearance.

While cleaning nails and removing polish may involve different tools and techniques, they do not illustrate the primary function of the abrasive quality found in an emery board. Strengthening hair is also not applicable, as the abrasive nature of an emery board is not meant to enhance the health or structural integrity of hair. Thus, the best description of the role of abrasiveness in an emery board is that it is utilized for smoothing hair edges.